Manufacture of locking nuts



June 13, 1933. w H. SCHALK MANUFACTURE OF LOCKING NUTS Filed Dec. 9, 1932 I I INVENTOR. Hzmnma Enamm ATTORNEY.

with threads.

Patented June 13, 1933' UNITED STATES PATENT oi-"FicE:

nnnmrcn m or VGUBTAVSBOBG um .uamz, GERMANY, Assmnon 'ro MASGHINENFAJBRIK AUGSBURG-NUERNBERG A. (1., OF nunnunnno, GERMAN/Y, n-

CORPORATION OF GERMANY IANUFAGDUBE OI LOCKING NUTS hppllcaflon filed December 9, 1982, Serial Ito.

M invention relates to the manufacture of elastic locking nuts. It is old to make such nuts by winding on edge a strip of elastic band steel having at one side a sharp edge which is located at the inner side during the winding and is intended to constitute the thread of the nut to be made. The thus obtained thread is objectionable in that it fits only badly to the thread of the correspondin bolt, and the procedure is complicated, or, besides the operation of winding the elastic steel band, the nut made in that manner must be separately treated along its circumferential surface in order to constitute a nut of proper design.

There exists also another method for the manufacture of elasticlocking nuts which, it is true, furnishes a better thread, but is also too complicated. In that method a steel band of conical transverse section so wound that the windings contact closely with one another, and the narrow side of the band is located at the inner side of the nut where the bore is that is to be provided The thus produced helical body is subdivided into such parts as are required for the indivdual nuts. These parts are then treated along their circum ferential surface, and finally the requisite thread is cut into everyone of the parts,

the windings being kept compressed during the thread cutting operation.

The present improved method of manufacturing elastic locking1 nuts is by far sinipler and dispenses wit the winding of a band, as well as with circumferential treatment. Dispensin with winding a band might be obtaine also b cutting threads into a tube, down throng the entire wall thickness of the same, but it would nevertheless be necessary to treat the outer surface of the tube so as to obtain nuts of the proper shape, and besides, the cutting off of such pieces as are required to constitute the individual nuts is also rather complicated.

' In contradistinction to those known procedures, I make use of a steel bar of hexagonal cross-section and I cut the windings or threads into this bar down to such a 0,431, and in Germany December 14, 1931.

depth that if the bar had already a bore corresponding to the bore of the nuts to be made, said windings or threads would at their bottom communicate with that bore. After a certain number of windings or threads has been cut into-the bar, also a circumferential groove is cut therein to the same depth as said windings, whereby'the respective number of windings (viz. as many as are requisite for a nut) is separated from the body part of the hexagonal bar. ow the core that has remained inside the wmdlngs is bored out, the helical piece thus obtained is axially compressed and thereupon the bolt thread is cut into the nut. Thereafter the nut is freed from the axial pressure, the width of the thread is nut, and the above-mentioned circumferen- I tial groove isjust in course of production. Figure 3 is again a similar view, the circumferential groove being finished and the core being bored out. Fi ure 4 is anaxial section throu h the mem ers holding the nut in compresse state, the nut being shown in side-view; andFigure 5 is a side-view of the locking nut in its finished state, this figure being to Fig. 4.

In Fig. 1, 0 denotes the steel bar of hexagonal transverse section, I) are windings or threads that have been cut into said bar, and c is the remaining core. When as many windings have been made as are required for a nut (generally three), a circumferential groove (1 (Figs. 2 and 3) is produced whereb the bar piece having the threads or win ings is separated from the body part of the bar, but is nevertheless-integrally connected therewith by the core 0. Now the' core drawn to an enlarged scale relative is bored out (Fig. 3) so that a helical piece is obtained which then is compressed by suitable means, for instance such as the parts a, f and 9 shown in Fig. 4 which parts need not be described in detail (Fig. 4). When the helical piece is in'this state, the bolt thread is cut into the nut, and then the latter is freed from the axial pressure so that it assumes its ultimate shape owin to the elasticity of the material ig. 5). lhe compressing members 6 and -"9 have bores e and gfor the passage of the tap (not shown). Finally, the nut is first heated and then cooled in well-known manner so as thereby to harden it in the usual way; If desired, the Width of the internal t read may be separately adjusted prior to the hardening, whereby at the same time the elasticity of the locking nut can be'regulated.

I claim:

1. The method of manufacturing elastic locking. nuts, consisting in cutting into a steel bar of hexagonal cross-section threads ;of such a depth that the diameter of the remaining core corresponds practically to the bolt hole in the finished nut, cutting into the bar after the last thread a roove having" the same depth as said threa s, boring out said core so that the thus produced bore communicates with said roove so as to thereby finally separate the t readed portion of the bar from its body part; compressing the separated threaded part causing its windings to contact with one another, cutting a bolt thread into the bore of the compressed nut,

and finally freeing the nut from its axial pressure,

2. The method of manufacturing lockin nuts, consisting iry'ci'lttin'g into a steel bar 0 hexagonal cross section a helical groove of such a depth that the diameter of the remaining core corres onds approximately to the diameter of the ore of the finished nut cuttin into the bar after the last winding of said helical groove a circumferential groove having the same depth as said helical one, boring out said core so that the thus produced bore communicates with both grooves so as to separate the grooved portion of the bar from its body part; compressing the separated helical portion causing its windingsto contact with one another, cutting a bolt thread into the bore of the compressed nut, liberating the nut from its axial pressure, and finally heating and cooling the nut to harden it.

In testimony whereof I aflix my signature.

HEINRICH SCHALK. 

